Hikers generally need a lightweight structure for sleeping outdoors that can be easily disassembled into a compact form and easily carried. Additionally, this structure needs to be easy to erect, without a multitude of easily lost parts that make the tent difficult to assemble, disassemble, and re-package for carrying.
Tents that satisfy the small size and few parts requirements have been developed without, however, satisfying the need for true ease of assembly and disassembly. Among these tents are ones in which a continuous band of spring coil is covered with fabric such that the device pops up into a tent, such as the structure illustrated in U.S. Pat. No. 3,675,667 to Miller. This device does not easily return to its disassembled form. A person must straddle the tent and struggle to loop one end toward the middle of the tent. Then the person must loop the other end over the first loop, all the while kneeling on the first loop to hold it in place. When this process has been accomplished, the user must fasten the ties on the tent so that the structure will not spontaneously spring back into erect shape.
Another structure of this nature is described in U.S. Pat. No. 3,990,463 to Norman. Again, a continuous band of spring steel is utilized. A length of spring steel is twisted 360 degrees and then connected to form a loop. Thus, when the loop is connected, each straight section is twisted 180 degrees. To relieve tension thus created, the frame naturally crosses over into a figure-eight shape.
The crossing point of the figure-eight forms the apex of the tent and the top and bottom of the figure-eight extend downwardly to touch the ground. To secure a length of the spring steel to the ground, stakes are used to tension the fabric panels of the tent, thereby compressing the frame toward the ground. The tent cannot stand independently, i.e., the tent must be staked to the ground.
Disassembly of this tent is awkward. The operator is first required to force the top and bottom of the figureeight shape together. The tension created by the 360 degree twist makes this difficult. The remainder of the collapsing motion is not possible until the first step is complete. Thus, this tent is not easily collapsed into compact form.
A spring loaded collapsible sunshade is disclosed in U.S. Pat. No. 4,815,784 to Zheng. This sunshade has two generally circular flexible spring steel loops which are positioned side by side. These loops are typically covered with fabric and have a fabric hinge in between them, completely separating one loop from the other. The sunshade is placed in the windshield of an automobile and held in place by rotating the visors down.
The Zheng sunshade is collapsed by folding the sunshade about the longitudinal axis of the fabric hinge such that one loop is arranged over the other. A bending and twisting operation collapses the sunshade into three concentric circles. Thus, the sunshade becomes approximately one-third the size of each initial circular loop of the sunshade.
However, the Zheng sunshade is not useful as a tent. It does not have sidewalls to connect the fabric covering the loops, which would allow wind, rain, snow, and other elements to enter. Additionally, the sunshade has no floor to protect a person from insects, snakes, plant life, etc. Most importantly, the sunshade has a fabric hinge between the two loops. Each loop is totally surrounded by fabric and totally separated from the other loop. The loops of the sunshade cannot form a frame for a tent since they can only lean against each other, providing little or no stability. Thus, the sunshade disclosed in the Zheng patent cannot provide a free-standing frame for a shelter.